I'm clueless when it comes to weight/circuit training. All the strength training I do is using my own body weight (push-ups, leg lifts, lunges, body squats, etc..)

The last time I saw my doctor she suggested I do some leg strengthening specifically for my hamstrings. Apparently, my quads have gotten very strong and my hamstrings are much weaker. When there is a disparity between the two, you are more likely to injure the hamstring (and I have strained it a few times)

My question is this...do I need to do a warmup before I use the weight machine? Is it OK to do the leg curls cold?

You can read a ton of information telling you to stretch before, but not after and then another ton telling you the exact opposite.

Lechuza is correct (although not sure where 7 minutes comes from). You need to raise your core temperature rather than just stretching by doing something like cycling, jogging, etc.

It is always advisable to do 1-2 (I like 2) warmup sets on whatever lift you are doing when using weights.

1 light set to prepare yourself and let you get your groove.
A 2nd warmup set to prepare your body for working in a specified manner under load.
Then begin your work sets on whatever you want to do.

People will often confuse soreness the next day with 'a good workout' rather than the fact they didn't warmup properly.

Find a qualified instructor to show you how to do stiff legged deadlifts correctly. Start off light and get the movement down correctly. These are by far the best exercise to do for your hamstrings and lower back.

Leg curls are okay (better than most machine exercises) but work the muscle in isolation which is not how the human body is supposed to work.

I've lifted weights for many years (mostly powerlifting) without any injuries and I have never done more than one light set to warm up on any lift. If you want powerful, balanced, overall leg strenth, do squats with a fairly wide stance(very narrow stance focuses on quads more).

I know, it sounds kinda superstitious. It's just an arbitrary number I go by to warm my legs. 5 minutes seemed too short and 10 seemed to long, so I just compromised.

I basically just want to get the muscles and connective tissues warmed up, but I don't need to get my pulse rate going for too long either. I definitely have to warm up and stretch before leg work outs. I've got some ham string issues. I shudder at the thought of doing squats without warming up, but that's just me.

As far as isolation of muscle groups, there is not a problem in doing that, unless you over train that one area only. Remember, we are not all symetrically perfect in our muscularity. We may need to isolate a muscle group in order to prevent stronger muscle groups from doing all of the work and stealing the benefit from the muscle group we are targeting.

And FingerorMoon? I believe that the good soreness is caused by a build up of lactic acid in the muscle group, which leaves you with some discomfort the next day. This cannot be avoided if your body is not used to the particular exercise, no matter how much warm up you do.

Sincerley,

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